Dragon Ball Z is way better dubbed. Goku's voice is just terrible in Japanese (I have nothing against Masako Nozawa but her role as Goku should have ended once he became an Adult. Otherwise she was a great voice actor for Dragon Ball.)

TV Series:
Spice and Wolf (both seasons) - Very good performances by both leads and a fine effort by the supporting cast.
Full Metal Panic (all seasons) - The actors for Sosuke, Tessa, and Kaname are great, and Kurz and Mao are even better!
Ah! My Goddess (TV series) - Excellent performances all around, but the shining stars are the voice actors for Belldandy, Urd, and Hild.
The Melancholy of Haruhi Suzmiya - Very well acted across the board.

The best TV series, which was already mentioned:

You're Under Arrest season 1 - This was even praised by the Japanese for its excellent dub cast! Everything works here!